|Kellogg, D. Wayne|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2008
Publication Date: 7/24/2008
Citation: Mashingo, M.S., Kellogg, D., Coblentz, W.K., Anschutz, K.S. 2008. Effect of harvest dates on yield and nutritive value of eastern gamgrass. Professional Animal Scientist. 24:363-373. Interpretive Summary: Concentrations of forage fiber components, crude protein, and ruminal decay characteristics of dry matter (DM) are important criteria for deciding the most appropriate time and stage of maturity for harvesting eastern gamagrass as hay. If hay of greater nutritive value is preferred, then harvest should occur in northern Arkansas at the beginning of June. According to this study, the expected crude protein (CP) would be greater than 10% at that time, but average DM yield would likely be < 8 Mg/ha. If hay is harvested later in June, CP would probably be less than 10%, but DM yields may increase to > 10 Mg/ha. The rumen's ability to digest DM was less desirable with advancing harvest dates. A decision to harvest earlier would result in greater nutritive value, and also may permit regrowth of the forage.
Technical Abstract: Yield of 'Pete' eastern gamagrass [Tripsacum dactyloides (L.) L.] was evaluated for 3 yr. Forage samples were harvested at 7-d intervals beginning on May 15 and ending on July 17, during 2000, 2001, and 2002. Samples from 2000 and 2001 were analyzed to determine nutrient composition. Canopy height increased (P < 0.01) during the 10-wk sampling period by 132, 89, and 132 cm and maximum height reached 225, 231, and 240 cm during 2000, 2001, and 2002, respectively. Increases in DM yield over harvest dates were quadratic, linear, and cubic (P < 0.01) and ranged from 1.25 to 10.04, 4.14 to 14.51, and 2.15 to 15.19 Mg/ha for 2000, 2001, and 2002, respectively. Concentrations of ADF and NDF for whole-plant samples increased with plant maturity during 2000 with NDF ranging from 31.1 to 44.5% and 65.9 to 78.5% during 2000 and ranged from 35.3 to 41.5% and 65.0 to 71.7% during 2001, respectively. Concentrations of CP declined from 14.4 to 6.3% and 14.7 to 6.6% during 2000 and 2001, respectively. The least numerical value for fraction A (the immediately soluble portion) and the potential extent of DM degradability were observed with eastern gamagrass that was harvested in early July. With limited fertilization eastern gamagrass demonstrated a tall growth habit and excellent DM yields. Harvest should be scheduled to provide the nutritive quality needed for a particular class of livestock.